/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.metrics;



import com.google.auto.value.AutoValue;

import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.annotations.Experimental.Kind;

import org.joda.time.Instant;



/** The result of a {@link Gauge} metric. */

@Experimental(Kind.METRICS)

@AutoValue

public abstract class GaugeResult {

  public abstract long getValue();



  public abstract Instant getTimestamp();



  public static GaugeResult create(long value, Instant timestamp) {

    return new AutoValue_GaugeResult(value, timestamp);

  }



  public static GaugeResult empty() {

    return EmptyGaugeResult.INSTANCE;

  }



  /** Empty {@link GaugeResult}, representing no values reported. */

  public static class EmptyGaugeResult extends GaugeResult {



    private static final EmptyGaugeResult INSTANCE = new EmptyGaugeResult();

    private static final Instant EPOCH = new Instant(0);



    private EmptyGaugeResult() {}



    @Override

    public long getValue() {

      return -1L;

    }



    @Override

    public Instant getTimestamp() {

      return EPOCH;

    }

  }

}